Optical position detection device, hand device, and display device with position detection function

ABSTRACT

A position detection device includes: a light source adapted to form a light intensity distribution of a detection light beam; a first detector adapted to receive a reflected light beam of the detection light beam reflected by an object in a detection area where the light intensity distribution is formed; a transmissive member disposed between the detection area and the light source, and between the detection area and the first detector, and having a first surface directed toward the detection area and a second surface directed toward the light source; a second detector adapted to receive a light beam reflected by the second surface out of the detection light beam; a position detector adapted to detect the object based on the detection result in the first detector; and a light blocking member disposed between the second detector and the detection area, and adapted to block the reflected light beam.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. application Ser. No.12/955,133 filed Nov. 29, 2010 which claims priority to the entiredisclosure of Japanese Patent Application No. 2009-273168, filed Dec. 1,2009 all of which are expressly incorporated by reference herein intheir entireties.

BACKGROUND

1. Technical Field

The present invention relates to an optical position detection devicefor optically detecting the position of a target object, and a handdevice and a display device with a position detection function eachprovided with the optical position detection device.

2. Related Art

As the optical position detection device for optically detecting theposition of the target object, there is proposed, for example, a device(see, e.g., JP-T-2003-534554 (Document 1; the term “JP-T” as used hereinmeans a published Japanese translation of a PCT patent application)) ofemitting detection light beams respectively from two light beam sourcestoward the target object via a transmissive member, and then receivingthe component of the detection light beams, which are reflected by thetarget object and transmitted through the transmissive member, by acommon light detector.

In the configuration described in Document 1 described above, theposition of the target object is detected based on the ratio between theemission intensities of the detection light beams when controlling thetwo light beam sources so that the receiving intensity of the lightdetector in the case in which the detection light beam emitted from oneof the two light beam sources is reflected by the target object and thereceiving intensity of the light detector in the case in which thedetection light beam emitted from the other of the two light beamsources is reflected by the target object become equal to each other.

In the configuration described in Document 1, since the method of usingthe spatial relationship between the detection light beams emitted fromthe two light beam sources is adopted, it is required to accuratelycontrol the emission intensities of the detection light beams from thelight beam sources. In order for achieving the above, although it isrequired to set the emission intensity of the light beam sources whilemonitoring inspection light beams emitted from the two light beamsources in the condition without the target object, Document 1 fails topropose the configuration therefor.

Further, in the configuration described in Document 1, some of thedetection light beam emitted from each of the two light beam sources isreflected by a surface of the transmissive member on the side oppositeto the side where the target object is located, and is received by thelight detector. Therefore, the reception intensity in the light detectoris a result of combining the reception intensity of the detection lightbeam reflected by the target object and the reception intensity of thelight beam other than the detection light beam reflected by the targetobject. Therefore, there arises a problem that the position detectionaccuracy is degraded if the position of the target object is detectedbased on the ratio between the emission intensities of the detectionlight beams when controlling the two light beam sources so that thereceiving intensity of the light detector in the case in which thedetection light beam emitted from one light beam source is reflected bythe target object and the receiving intensity of the light detector inthe case in which the detection light beam emitted from the other lightbeam source is reflected by the target object become equal to eachother.

SUMMARY

An advantage of some aspects of the invention is to provide an opticalposition detection device in which some of the detection light emittedfrom the light source section is monitored as a blank light beam havinga constant intensity irrespective of presence or absence of the targetobject and is used for setting the drive condition in the light sourcesection, and the blank light does not hinder detection of the positionof the target object, and a hand device and a display device with aposition detection function, each having the optical position detectiondevice.

According to an aspect of the invention, there is provided an opticalposition detection device adapted to optically detect a position of atarget object, including a light source section adapted to form a lightintensity distribution of a detection light beam in a detection area setin an emission direction of the detection light beam, a first lightdetector which a position detecting reflected light beam reflected bythe target object in the detection area enters and a blank light beamfailing to pass through the detection area fails to enter out of thedetection light beam emitted from the light source section, a secondlight detector which the position detecting reflected light beam failsto enter and the blank light beam enters, and a position detectionsection adapted to detect the target object in the detection area basedon the detection result in the first light detector.

In this aspect of the invention, the light source device emits thedetection light beam to form the light intensity distribution in thedetection area. Further, the position detecting reflected light beamreflected by the target object is detected by the first light detector.Here, since the light intensity distribution has a certain relationshipbetween the position in the detection area and the intensity, bypreviously figuring out the relationship between the position and theintensity of the detection light beam, the position detection sectioncan detect the position of the target object based on the lightreception result of the first light detector. Further, in this aspect ofthe invention, there is provided the second light detector to which theposition detecting reflected light beam reflected by the target objectin the detection area out of the detection light beam emitted from thelight source section is not input, and the blank light beam not passingthrough the detection area enters the second light detector. Therefore,since the second light detector can monitor the blank light beamirrespective of whether or not the target object exists in the detectionarea, it is possible to set the emission intensity of the detectionlight beam from the light source section to optimum conditions based onthe monitoring result. Therefore, since it is not required to monitorthe blank light beam by the first light detector, it is possible toadopt the configuration in which the position detecting reflected lightbeam enters the first light detector while the blank light beam does notenter the first light detector. Therefore, since the influence of theblank light beam is eliminated from the light reception result in thefirst light detector, the position detection section can detect theposition of the target object without being unnecessarily affected bythe blank light beam.

In this aspect of the invention, it is preferable that a light blockingmember adapted to block the position detecting reflected light beam fromentering the second light detector is disposed between the second lightdetector and the detection area. According to this configuration, theposition detecting reflected light beam can be prevented from enteringthe second light detector only by adding the configuration of providingthe light blocking member.

In this aspect of the invention, it is possible to adopt a configurationin which a transmissive member having a first surface directed towardthe detection area and a second surface directed toward the light sourcesection is disposed between the light source section and the detectionarea, and the blank light beam corresponds to a light beam reflected bythe second surface of the transmissive member out of the detection lightbeam emitted from the light source section. According to thisconfiguration, out of the detection light beam emitted from the lightsource section, the blank light beam can be deflected toward the side onwhich the second light detector is located.

In this aspect of the invention, it is preferable that the first lightdetector has a light receiving section disposed close to the secondsurface of the transmissive member. According to this configuration, theblank light beam can be prevented from entering the first light detectorwith a relatively simple configuration.

In this aspect of the invention, it is preferable that the second lightdetector is disposed at a position overlapping the first light detectorin the normal direction with respect to the second surface on the sideopposite to the side on which the transmissive member is located withrespect to the first light detector. According to this configuration,the position detecting reflected light beam can be prevented fromentering the second light detector with a relatively simpleconfiguration.

In this aspect of the invention, it is possible to adopt a configurationin which the light source section forms a first light intensitydistribution in which the intensity varies in a direction from one sidetoward the other side in the detection area, and a second lightintensity distribution having an intensity variation in a direction fromthe other side toward the one side different from the first lightintensity distribution, and the position detection section detects aposition of the target object based on a comparison result between adetection result in the first light detector when forming the firstlight intensity distribution, and a detection result in the first lightdetector when forming the second light intensity distribution.

In this aspect of the invention, it is also possible to adopt aconfiguration in which the light source section forms a first lightintensity distribution in which the intensity varies in a direction fromone side toward the other side in the detection area, and a second lightintensity distribution having an intensity variation in a direction fromthe other side toward the one side different from the first lightintensity distribution, and varies an emission intensity of thedetection light beam so that the detection result in the first lightdetector when forming the first light intensity distribution and thedetection result in the first light detector when forming the secondlight intensity distribution become equal to each other, and theposition detection section detects a position of the target object basedon one of the emission intensity of the detection light beam from thelight source section after varying the emission intensity of thedetection light beam and the detection result in the second lightdetector.

By adopting such a detection method, even in the case in which theenvironment light enters the first light detector and the second lightdetector, the position of the target object can be detected withoutbeing affected by the environment light.

The optical position detection device to which the invention is appliedcan be applied to a hand device, and in this case, the hand device isprovided with a hand for gripping the target object.

The optical position detection device to which the invention is appliedcan be applied to the display device with a position detection function,and in this case, the display device with a position detection functionis provided with an image generation device for displaying an image inan area overlapping the detection area.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIGS. 1A and 1B are explanatory diagrams schematically showing aprincipal part of an optical position detection device according to afirst embodiment of the invention.

FIG. 2 is an explanatory diagram showing an overall configuration of theoptical position detection device according to the first embodiment ofthe invention.

FIG. 3 is an explanatory diagram showing how the blank light beam in thecondition in which the target object is absent reaches a second lightdetector in the optical position detection device according to the firstembodiment of the invention.

FIGS. 4A and 4B are explanatory diagrams showing the principle ofX-coordinate detection used in the optical position detection deviceaccording to the first embodiment of the invention.

FIGS. 5A and 5B are explanatory diagrams showing the content of thesignal processing in the optical position detection device according tothe first embodiment of the invention.

FIGS. 6A and 6B are explanatory diagrams showing the principle ofdetecting the distance between a transmissive member and the targetobject in the optical position detection device according to the firstembodiment of the invention.

FIGS. 7A and 7B are explanatory diagrams schematically showing aprincipal part of an optical position detection device according to asecond embodiment of the invention.

FIG. 8 is an explanatory diagram showing an overall configuration of theoptical position detection device according to the second embodiment ofthe invention.

FIGS. 9A through 9D are explanatory diagrams of detection light beamsemitted from respective light emitting elements in the optical positiondetection device according to the second embodiment of the invention.

FIGS. 10A through 10D are explanatory diagrams showing light intensitydistributions used for coordinate detection formed by the detectionlight beams emitted from the light emitting elements in the opticalposition detection device according to the second embodiment of theinvention.

FIGS. 11A and 11B are explanatory diagrams of a robot arm using theoptical position detection device to which the invention is applied as ahand device.

FIGS. 12A and 12B are explanatory diagrams schematically showing adisplay device with a position detection function having an opticalposition detection device, to which the invention is applied, as a touchpanel.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, some embodiments of the invention will be explained indetail with reference to the accompanying drawings. It should be notedthat in the explanation described below it is assumed that X-axis,Y-axis, and Z-axis intersect with each other, and the direction in whichthe transmissive member and the target object are distant from eachother is a Z-axis direction. Further, in the drawings referred to below,things are shown assuming one side of the X-axis direction as an X1side, the other side thereof as an X2 side, one side of the Y-axisdirection as a Y1 side, and the other side thereof as a Y2 side.

First Embodiment

Overall Configuration

FIGS. 1A and 1B are explanatory diagrams of a principal part of theoptical position detection device according to a first embodiment of theinvention, wherein FIG. 1A is an explanatory diagram showing athree-dimensional arrangement of constituents of the optical positiondetection device, and FIG. 1B is an explanatory diagram showing atwo-dimensional arrangement of the constituents of the optical positiondetection device. FIG. 2 is an explanatory diagram showing an overallconfiguration of the optical position detection device according to thefirst embodiment of the invention. FIG. 3 is an explanatory diagramshowing how the blank light beam in the condition in which the targetobject is absent reaches a second light detector in the optical positiondetection device according to the first embodiment of the invention.

In FIGS. 1A, 1B, and 2, the optical position detection device 10according to the present embodiment is an optical sensor device fordetecting the position of the target object Ob located on the side of afirst surface 41 of a transmissive member 40 having a sheet-like shapeor a plate-like shape, and is used as a tactile sensor of a robot handdevice described later or a touch panel.

In order for performing such detection, the optical position detectiondevice 10 according to the present embodiment is provided with thetransmissive member 40 having a sheet-like shape or a plate-like shapeand having a first surface 41 directed along the XY plane, a lightsource section 11 for emitting detection light beams L2 from the side ofa second surface 42 opposite to the side of the first surface 41 in thetransmissive member 40, and a first light detector 30 for detectingposition detecting reflected light beams L3 reflected by the targetobject Ob and transmitted to the side of the second surface 42 of thetransmissive member 40. A light receiving section 31 of the first lightdetector 30 is opposed to the second surface 42 of the transmissivemember 42.

In the present embodiment, the light source section 11 is provided witha plurality of light emitting elements 12, and these light emittingelements 12 are driven by a light source drive section 14 shown in FIG.2. In the present embodiment, the light source section 11 is providedwith two light emitting elements 12A, 12B as the plurality of lightemitting elements 12, and the light emitting elements 12A, 12B arelocated distantly in the X-axis direction and have the respective lightemitting surfaces directed toward the transmissive member 40. The lightemitting elements 12A, 12B are each composed of a light emitting diode(LED) or the like, and in the present embodiment, the light emittingelements 12A, 12B respectively emit the detection light beams L2(detection light beams L2 a, L2 b) of infrared light beams, as diverginglight beams.

The first light detector 30 is composed of a photodiode or aphototransistor having the light receiving section 31 directed towardthe transmissive member 40, and in the present embodiment, a photodiodeis used as the first light detector 30. In the present embodiment, thefirst light detector 30 is disposed on the side of the second surface 42of the transmissive member 40, and between the positions at which thetwo light emitting elements 12A, 12B are disposed.

In the optical position detection device 10 having the configurationdescribed above, a detection area 10R is set on the side of the firstsurface 41 of the transmissive member 40 (a space on the emission sideof the detection light beams L2 from the light source section 11).Therefore, when the light emitting elements 12A, 12B of the light sourcesection 11 are put on sequentially to emit the detection light beams L2a, L2 b, the detection light beams L2 a, L2 b are transmitted throughthe transmissive member 40, and form respective X-coordinate detectinglight intensity distributions (an X-coordinate detecting first lightintensity distribution L2Xa and an X-coordinate detecting second lightintensity distribution L2Xb) each having the intensity varying along theX-axis direction on the side of the first surface 41 (the detection area10R) as described later with reference to FIGS. 4A and 4B. In such anX-coordinate detecting first light intensity distribution L2Xa, theintensity decreases in the X-axis direction from the one side X1 to theother side X2, while in the X-coordinate detecting second lightintensity distribution L2Xb, the intensity decreases in the X-axisdirection from the other side X2 to the one side X1. Such variations canbe made to be linear variations by controlling the light intensitydistributions within the limited space, namely the detection area 10R.Therefore, in the optical position detection device according to thepresent embodiment, the position (X-coordinate) of the target object Obin the in-plane direction (the X-axis direction) of the transmissivemember 40 can be detected using the X-coordinate detecting first lightintensity distribution L2Xa, the X-coordinate detecting second lightintensity distribution L2Xb, and the detection result in the first lightdetector 30 as described later.

Further, when the light emitting elements 12A, 12B of the light sourcesection 11 are put on simultaneously to emit the detection light beamsL2 a, L2 b, the detection light beams L2 a, L2 b are transmitted throughthe transmissive member 40, and form a distance detecting lightintensity distribution L2Zab having the intensity varying along thenormal direction (the Z-axis direction) with respect to the firstsurface 41 on the side of the first surface 41 (the detection area 10R)as described later with reference to FIGS. 6A and 6B. In such a distancedetecting light intensity distribution L2Zab, the intensity decreasesmonotonically along the direction of increasing the distance from thefirst surface 41 of the transmissive member 40, and such a variation canbe made to be a linear variation by controlling the light intensitydistribution within the limited space of the detection area 10R.Further, in the distance detecting light intensity distribution L2Zab,the intensity is constant along the X-axis direction. Therefore, in theoptical position detection device 10 according to the presentembodiment, as described later, the distance LZ (the Z-coordinate)between the target object Ob and the transmissive member 40 can bedetected using the distance detecting light intensity distribution L2Zaband the detection result in the first light detector 30.

In the present embodiment, for the purpose of canceling an influence ofoutside light, the light source section 11 of the optical positiondetection device 10 is also provided with a light emitting element 12Rfor reference, which emits a reference light beam L2 r toward the firstlight detector 30. Similarly to the light emitting elements 12 (thelight emitting element 12A, 12B) for position detection, the lightemitting element 12R for reference is also composed of a light emittingdiode (LED) or the like, and the light emitting element 12R emits thereference light beam L2 r, which is an infrared light beam, as adiverging light beam. It should be noted that the light emitting element12R for reference is provided with a light blocking cover (not shown),so that the reference light beam L2 r emitted from the light emittingelement 12R for reference does not enter the side (the detection area10R) of the first surface 41 of the transmissive member 40.

Configuration of Second Light Detector

As shown in FIGS. 1A, 1B, and 2, in the optical position detectiondevice 10 the first light detector 30 is located on the side of thesecond surface 42 of the transmissive member 40 and has the lightreceiving section 31 directed toward the second surface 42, and thelight receiving section 31 is disposed close to the second surface 42.

Further, in the optical position detection device 10 according to thepresent embodiment, on the side of the second surface 42 of thetransmissive member 40 there is disposed a second light detector 60, andthe second light detector 60 also has a light receiving section 61directed toward the second surface 42 similarly to the first lightdetector 30. Similarly to the first light detector 30, the second lightdetector 60 is composed of a photodiode or a phototransistor, and in thepresent embodiment, a photodiode is used as the second light detector60.

Here, the second light detector 60 is disposed at a position overlappingthe first light detector 30 in the normal direction with respect to thesecond surface 42 on the side opposite to the side where thetransmissive member 40 is located with respect to the first lightdetector 30. Further, in a space between the first light detector 30 andthe second light detector 60 included in a space between thetransmissive member 40 and the second light detector 60, there isdisposed a plate-like light blocking member 70 capable of blockinginfrared light beams, and therefore the light blocking member 70intervenes between the detection area 10R and the second light detector60. The light blocking member 70 has a size slightly larger than that ofthe second light detector 60, and has a predetermined distance from thesecond light detector 60.

In the optical position detection device 10 configured as describedabove, when the light source section 11 emits the detection light beamsL2 (the detection light beams L2 a, L2 b) toward the side where thetransmissive member 40 and the detection area 10R are located, some ofeach of the detection light beams L2 is transmitted through thetransmissive member 40, and forms the light intensity distribution inthe detection area 10R. Further, some of each of the detection lightbeams L2 (the detection light beams L2 a, L2 b) emitted from the lightsource section 11 becomes the blank light beam L0 (a detection lightbeam L0 a or a detection light beam L0 b), which is reflected by thesecond surface 42 of the transmissive member 40, and fails to reach thedetection area 10R.

Here, since the light receiving section 31 of the first light detector30 is opposed to the second surface 42, the position detecting reflectedlight beams L3 reflected by the target object Ob in the detection area10R enter the first light detector 30. It should be noted that since thelight receiving section 31 of the first light detector 30 is close tothe second surface 42, the blank light beams L0, which are reflected bythe second surface 42 of the transmissive member 40 and fail to passthrough the detection area 10R, fail to enter the first light detector30.

In contrast thereto, since the first light detector 30 and the lightblocking member 70 intervene between the second light detector 60, andthe transmissive member 40 and the detection area 10R, the positiondetecting reflected light beams L3 reflected by the target object Ob inthe detection area 10R fail to enter the second light detector 60. Itshould be noted that since the light blocking member 70 is fairly smallin view of the size of the transmissive member 40 and the distancebetween the light emitting elements 12, the blank light beams L0, whichare reflected by the second surface 42 of the transmissive member 40 andfail to reach the detection area 10R, enter the second light detector60.

It should be noted that in the present embodiment, environment light Lcsuch as outside light enters both of the first light detector 30 and thesecond light detector 60. Further, the reference light beam L2 r emittedfrom the light emitting element 12R for reference partially enters thefirst light detector 30, and partially enters the second light detector60 as the blank light beam L0 r.

Configuration of Position Detection Section etc.

As shown in FIG. 2, in the optical position detection device 10according to the present embodiment, the light source drive section 14of the light source section 11 is provided with a light source drivecircuit 140 for driving the light emitting elements 12 and so on, and alight source control section 145 for controlling a lighting pattern ofeach of the plurality of light emitting elements 12 via the light sourcedrive circuit 140. The light source drive circuit 140 is provided with alight source drive circuit 140 a for driving the light emitting element12A, a light source drive circuit 140 b for driving the light emittingelement 12B, and a light source drive circuit 140 r for driving thelight emitting element 12R for reference. The light source controlsection 145 controls all of the light source drive circuits 140 a, 140b, and 140 r.

The position detection section 50 is electrically connected to the firstlight detector 30, and the detection result in the first light detector30 is output to the position detection section 50. The positiondetection section 50 is provided with a signal processing section 55provided with an amplifier and so on, an X-coordinate detection section51, and a distance detection section 53 (a Z-coordinate detectionsection), and the light source drive section 14 and the positiondetection section 50 operate in conjunction with each other to performthe position detection described later.

An emission intensity monitoring section 16 is electrically connected tothe second light detector 60, and the detection result in the secondlight detector 60 is output to the emission intensity monitoring section16. Such an emission intensity monitoring section 16 monitors theemission intensity of each of the light emitting elements 12 (the lightemitting elements 12A, 12B) for position detection and the lightemitting element 12R for reference based on the detection result of theblank light beams L0 by the second light detector 60, and the lightsource control section 145 sets an initial value of the emissionintensity of each of the light emitting elements 12 (the light emittingelements 12A, 12B) for position detection and the light emitting element12R for reference based on the monitoring result.

Initial Setting of Emission Intensities of Light Emitting Elements 12and 12R

FIG. 3 is an explanatory diagram showing how the blank light beams L0 inthe condition in which the target object Ob is absent reach the secondlight detector 60 in the optical position detection device 10 accordingto the first embodiment of the invention. As shown in FIG. 3, in orderfor setting the initial values of the emission intensities of the lightemitting elements 12 (the light emitting elements 12A, 12B) for positiondetection and the light emitting element 12R for reference in theoptical position detection device 10 according to the presentembodiment, the light emitting elements 12A, 12B, 12R are put onsequentially in the condition in which the target object Ob is absentfrom the detection area 10R, and the light source control section 145sets the initial values of the emission intensities of the lightemitting elements 12A, 12B, and 12R based on the detection result of theblank light beams L0 (the blank light beams L0 a, L0 b, and L0 r) in thesecond light detector 60 at that time.

Detection of X Coordinate

In the optical position detection device 10 according to the presentembodiment, since the two light emitting elements (the light emittingelements 12A, 12B) are disposed at positions distant from each other inthe X-axis direction, the X-coordinate of the target object Ob can bedetected using the light intensity distribution formed by the lightemitting element 12A and the light intensity distribution formed by thelight emitting element 12B. Therefore, the configuration of the lightintensity distribution and the principle of the X-coordinate detectionwill be explained with reference to FIGS. 4A and 4B.

FIGS. 4A and 4B are explanatory diagrams showing the principle of theX-coordinate detection used in the optical position detection deviceaccording to the first embodiment of the invention, wherein FIG. 4A isan explanatory diagram showing the light intensity distributions in theX-axis direction of the detection light beams and so on, and FIG. 4B isan explanatory diagram showing how the light intensity distributions ofthe detection light beams are adjusted so that the intensities of thedetection light beams reflected by the target object Ob become equal toeach other.

In the optical position detection device 10 according to the presentembodiment, when detecting the X-coordinate, firstly in the X-coordinatedetecting first period, the light emitting element 12A is put on whileputting off the light emitting element 12B to thereby form anX-coordinate detecting first light intensity distribution L2Xa in whichthe intensity monotonically decrease in the X-axis direction from theone side X1 toward the other side X2 as shown in FIG. 4A. Further, in anX-coordinate detecting second period, the light emitting element 12B isput on while putting off the light emitting element 12A to thereby formthe X-coordinate detecting second light intensity distribution L2Xb inwhich the intensity monotonically decreases in the X-axis direction fromthe other side X2 toward the one side X1. Preferably, after forming theX-coordinate detecting first light intensity distribution L2Xa in whichthe intensity linearly decreases in the X-axis direction from the oneside X1 toward the other side X2 in the X-coordinate detecting firstperiod, the X-coordinate detecting second light intensity distributionL2Xb in which the intensity linearly decreases in the X-axis directionfrom the other side X2 toward the one side X1 is formed in theX-coordinate detecting second period.

Therefore, when the target object Ob is disposed in the detection area10R, the detection light beams L2 are reflected by the target object Ob,and some of each of the reflected light beams is detected by the firstlight detector 30. Here, by previously setting the X-coordinatedetecting first light intensity distribution L2Xa formed in theX-coordinate detecting first period and the X-coordinate detectingsecond light intensity distribution L2Xb formed in the X-coordinatedetecting second period to be predetermined distributions, theX-coordinate detection section 51 can detect the X-coordinate of thetarget object Ob based on the detection result in the light detector 30using the following method, for example.

For example, in a first method, a comparison result between theX-coordinate detecting first light intensity distribution L2Xa and theX-coordinate detecting second light intensity distribution L2Xb shown inFIG. 4A is used. More specifically, since the X-coordinate detectingfirst light intensity distribution L2Xa and the X-coordinate detectingsecond light intensity distribution L2Xb are previously set to thepredetermined distributions, the difference between the X-coordinatedetecting first light intensity distribution L2Xa and the X-coordinatedetecting second light intensity distribution L2Xb is also setpreviously to be a predetermined function. Therefore, by comparing thedetection value LXa in the first light detector 30 when forming theX-coordinate detecting first light intensity distribution L2Xa in theX-coordinate detecting first period and the detection value LXb in thefirst light detector 30 when forming the X-coordinate detecting secondlight intensity distribution L2Xb in the X-coordinate detecting secondperiod with each other, and then obtaining the difference between thetwo detection values, the X-coordinate of the target object Ob can bedetected.

According to such a method, even in the case in which the environmentlight Lc other than the detection light beams L2 such as the infraredcomponent included in the outside light enters the first light detector30, the intensity of the infrared component included in the environmentlight Lc is canceled out when obtaining the difference between thedetection values LXa, LXb, and therefore, the infrared componentincluded in the environment light Lc never exerts an influence on thedetection accuracy. Further, since the blank light beams L0 (the blanklight beams L0 a, L0 b) are not included in the detection values LXa,LXb in the first light detector 30, the X-coordinate detection section51 can detect the X-coordinate of the target object Ob based on thedetection result in the first light detector 30 without being affectedby the blank light beams L0 (the blank light beams L0 a, L0 b). Itshould be noted that it is also possible to detect the X-coordinate ofthe target object Ob based on the ratio between the detection valuesLXa, LXb.

Then, in a second method, the X-coordinate of the target object Ob isdetected based on the adjustment value having been used when adjustingthe control value (the drive current value) for the light emittingelements 12 so that the detection value LXa in the first light detector30 when forming the X-coordinate detecting first light intensitydistribution L2Xa in the X-coordinate detecting first period and thedetection value LXb in the first light detector 30 when forming theX-coordinate detecting second light intensity distribution L2Xb in theX-coordinate detecting second period become equal to each other. Such amethod can be applied to the case in which the intensity in theX-coordinate detecting first light intensity distribution L2Xa and theX-coordinate detecting second light intensity distribution L2Xb shown inFIG. 4A varies linearly with respect to the X-coordinate. In the presentembodiment, the detection light beam Lb out of the detection light beamLa emitted by the light emitting element 12A and the detection lightbeam Lb emitted by the light emitting element 12B is used as thereference light beam in the first period, and the detection light beamLa is used as the reference light beam in the second period, and thedifferential between the detection light beam and the reference lightbeam is used.

Firstly, as shown in FIG. 4A, the X-coordinate detecting first lightintensity distribution L2Xa and the X-coordinate detecting second lightintensity distribution L2Xb are formed in the X-coordinate detectingfirst period and the X-coordinate detecting second period so that theabsolute values are equal to each other and the directions are oppositeto each other along the X-axis direction. It is understood that if thedetection value LXa in the first light detector 30 in the X-coordinatedetecting first period and the detection value LXb in the first lightdetector 30 in the X-coordinate detecting second period are equal toeach other, the target object Ob is located at the center in the X-axisdirection.

In contrast thereto, in the case in which the detection value LXa in thefirst light detector 30 in the X-coordinate detecting first period andthe detection value LXb in the first light detector 30 in theX-coordinate detecting second period are different from each other, thecontrol values (the drive current values) to the light emitting elements12 are adjusted so that the detection values LXa, LXb become equal toeach other, and as shown in FIG. 4B, the X-coordinate detecting firstlight intensity distribution L2Xa is formed again in the X-coordinatedetecting first period, and the X-coordinate detecting second lightintensity distribution L2Xb is formed again in the X-coordinatedetecting second period. As a result, if the detection value LXa in thefirst light detector 30 in the X-coordinate detecting first period andthe detection value LXb in the first light detector 30 in theX-coordinate detecting second period become equal to each other, theX-coordinate of the target object Ob can be detected based on the ratio,the difference, or the like between the adjustment value ΔLXa of thecontrol value to the light emitting elements 12 in the X-coordinatedetecting first period and the adjustment value ΔLXb of the controlvalue to the light emitting elements 12 in the X-coordinate detectingsecond period.

According to such a method, even in the case in which the environmentlight Lc other than the detection light beams L2 such as the infraredcomponent included in the outside light enters the first light detector30, the intensity of the infrared component included in the environmentlight Lc is canceled out when performing adjustment of the controlvalues to the light emitting elements 12 so that the detection valuesLXa, LXb become equal to each other, and therefore, the infraredcomponent included in the environment light Lc never exerts an influenceon the detection accuracy. Further, since the blank light beams L0 (theblank light beams L0 a, L0 b) are not included in the detection valuesLXa, LXb in the first light detector 30, the X-coordinate detectionsection 51 can detect the X-coordinate of the target object Ob based onthe detection result in the first light detector 30 without beingaffected by the blank light beams L0 (the blank light beams L0 a, L0 b).

It should be noted that although in the method described above both ofthe control values to the light emitting elements 12A, 12B for positiondetection are adjusted, it is also possible to adjust either one of thecontrol values.

Further, although in the method described above the X-coordinate of thetarget object Ob is detected based on the control values to the lightemitting elements 12A, 12B for position detection, it is also possibleto detect the X-coordinate of the target object Ob based on the lightreception result in the second light detector 60 when controlling thelight emitting elements 12A, 12B so that the detection values LXa, LXbbecome equal to each other.

When obtaining the position information of the target object Ob in theX-axis direction based on the detection result in the light detector 30in such a manner as described above, it is also possible to adopt aconfiguration of using a microprocessor unit (MPU) as the positiondetection section 50, and thus executing predetermined software (anoperation program) by the microprocessor unit, thereby performing theprocess. Further, as explained later with reference to FIGS. 5A and 5B,it is also possible to adopt a configuration of performing the processwith a signal processing section using hardware such as a logic circuit.

Configuration Example of Position Detection Section 50

FIGS. 5A and 5B are explanatory diagrams showing the content of thesignal processing in the optical position detection device 10 accordingto the first embodiment of the invention, wherein FIG. 5A is anexplanatory diagram of the position detection section 50 of the opticalposition detection device 10 according to the first embodiment of theinvention, and FIG. 5B is an explanatory diagram showing the content ofthe process in an emission intensity compensation instruction section ofthe position detection section 50. The position detection section 50described here adopts the method of detecting the distance LZ (aZ-coordinate) between the target object Ob and the first surface 41 ofthe transmissive member 40 based on the adjustment values when adjustingthe control value (the drive current value) to the light emittingelements 12A, 12B for position detection and the control value (thedrive current value) to the light emitting element 12R for reference sothat the detection value LXa of the detection light beam L2 a in thefirst light detector 30 and the detection value LXb of the detectionlight beam L2 b in the first light detector 30 become equal to eachother.

As shown in FIG. 5A, in the optical position detection device 10according to the present embodiment, the light source drive circuit 140is represented as being arranged to apply a drive pulse with apredetermined current value to the light emitting element 12A forposition detection via a variable resistor 111 in the X-coordinatedetecting first period, and apply a drive pulse with a predeterminedcurrent value to the light emitting element 12B for position detectionvia a variable resistor 112 and an inverting circuit 113 in theX-coordinate detecting second period. Therefore, as a result, the lightsource drive circuit 140 applies the drive pulses with phases reverse toeach other to the light emitting elements 12A, 12B in the X-coordinatedetecting first period and the X-coordinate detecting second period,respectively. Further, the light beam, which is the first positiondetection light beam L2 a forming the X-coordinate detecting first lightintensity distribution L2Xa and reflected by the target object Ob, isreceived by the common first light detector 30 in the X-coordinatedetecting first period, and the light beam, which is the second positiondetection light beam L2 b forming the X-coordinate detecting secondlight intensity distribution L2Xb and reflected by the target object Ob,is received by the common first light detector 30 in the X-coordinatedetecting second period. In a light intensity signal generation circuit150, a resistor 30 r with a resistance of about 1 kΩ is connected inseries to the first light detector 30, and a bias voltage Vb is appliedbetween the both ends thereof.

In such a light intensity signal generation circuit 150, the positiondetection section 50 is electrically connected to the connection pointP1 between the first light detector 30 and the resistor 30 r. Adetection signal Vc output from the connection point P1 between thefirst light detector 30 and the resistor 30 r is expressed by thefollowing formula.Vc=V30/(V30+(resistance value of the resistor 30r))

-   V30: an equivalent resistance of the first light detector 30

Therefore, in comparison between the case in which the environment lightLc fails to enter the first light detector 30 and the case in which theenvironment light Lc enters the first light detector 30, the level andthe amplitude of the detection signal Vc become greater in the case inwhich the environment light Lc enters the first light detector 30.

The position detection section 50 is generally composed of a positiondetection signal extraction circuit 190, a position detection signalseparation circuit 170, and the emission intensity compensationinstruction circuit 180.

The position detection signal extraction circuit 190 is provided with afilter 192 composed of a capacitor of about 1 nF, and the filter 192functions as a high-pass filter for eliminating a direct-currentcomponent from the signal output from the connection point P1 betweenthe first light detector 30 and the resistor 30 r. Therefore, due to thefilter 192, only the position detection signal Vd detected by the firstlight detector 30 in the X-coordinate detecting first period and theX-coordinate detecting second period is extracted from the detectionsignal Vc output from the connection point P1 between the first lightdetector 30 and the resistor 30 r. Therefore, since the intensity of theenvironment light Lc can be regarded as constant during a certain periodof time while the detection light beams L2 and the reference light beamL2 r are modulated, the low-frequency component or the direct-currentcomponent caused by the environment light Lc can be eliminated by thefilter 192.

Further, the position detection signal extraction circuit 190 has anadder circuit 193 provided with a feedback resistor 194 of about 220 kΩin the posterior stage of the filter 192, and the position detectionsignal Vd extracted by the filter 192 is output to the positiondetection signal separation circuit 170 as a position detection signalVs obtained by superimposing the position detection signal Vd on avoltage V/2 half as high as the bias voltage Vb.

The position detection signal separation circuit 170 is provided with aswitch 171 for performing a switching operation in sync with the drivepulse applied to the light emitting element 12A in the X-coordinatedetecting first period, a comparator 172, and capacitors 173electrically connected respectively to input lines of the comparator172. Therefore, when the position detection signal Vs is input to theposition detection signal separation circuit 170, the position detectionsignal separation circuit 170 outputs the effective value Vea of theposition detection signal Vs in the X-coordinate detecting first periodand the effective value Veb of the position detection signal Vs in theX-coordinate detecting second period alternately to the emissionintensity compensation instruction circuit 180.

The emission intensity compensation instruction circuit 180 compares theeffective values Vea, Veb with each other to perform the process shownin FIG. 5B, and outputs the control signal Vf to the light source drivecircuit 140 so that the effective value Vea of the position detectionsignal Vs in the X-coordinate detecting first period and the effectivevalue Veb of the position detection signal Vs in the X-coordinatedetecting second period have the same level. In other words, theemission intensity compensation instruction circuit 180 compares theeffective value Vea of the position detection signal Vs in theX-coordinate detecting first period and the effective value Veb of theposition detection signal Vs in the X-coordinate detecting second periodwith each other, and then keeps the present drive condition if they areequal to each other. In contrast thereto, if the effective value Vea ofthe position detection signal Vs in the X-coordinate detecting firstperiod is lower than the effective value Veb of the position detectionsignal Vs in the X-coordinate detecting second period, the emissionintensity compensation instruction circuit 180 makes the resistancevalue of the variable resistor 111 decrease to thereby increase theintensity of the light emitted from the light emitting element 12 in theX-coordinate detecting first period. Further, if the effective value Vebof the position detection signal Vs in the X-coordinate detecting secondperiod is lower than the effective value Vea of the position detectionsignal Vs in the X-coordinate detecting first period, the emissionintensity compensation instruction circuit 180 makes the resistancevalue of the variable resistor 112 decrease to thereby increase theintensity of the emission light in the X-coordinate detecting secondperiod.

In such a manner as described above, the optical position detectiondevice 10 controls the control value (the current value) of each of thelight emitting elements 12 using the emission intensity compensationinstruction circuit 180 of the position detection section 50 so that thedetection amounts by the first light detector 30 in the X-coordinatedetecting first period and the X-coordinate detecting second periodbecome equal to each other. Therefore, since the information regardingthe control values to the light emitting elements 12, with which theeffective value Vea of the position detection signal Vs in theX-coordinate detecting first period and the effective value Veb of theposition detection signal Vs in the X-coordinate detecting second periodhave the same level, exists in the emission intensity compensationinstruction circuit 180, by outputting the information to the distancedetection section 53 as the position detection signal Vg, the distancedetection section 53 can obtain the X-coordinate of the target objectOb.

Further, in the present embodiment, the filter 192 eliminates thedirect-current component caused by the environment light Lc from thedetection signal Vc output from the connection point P1 between thefirst light detector 30 and the resistor 30 r to thereby extract theposition detection signal Vd in the position detection signal extractioncircuit 190. Therefore, even in the case in which the detection signalVc output from the connection point P1 between the first light detector30 and the resistor 30 r includes the signal component due to theinfrared component of the environment light Lc, the influence of suchenvironment light Lc can be canceled.

Distance Detecting Light Intensity Distribution and Method of DetectingDistance LZ

FIGS. 6A and 6B are explanatory diagrams showing the principle ofdetecting the distance between the transmissive member and the targetobject in the optical position detection device according to the firstembodiment of the invention, wherein FIG. 6A is an explanatory diagramshowing the light intensity distribution of the detection light beam inthe Z-axis direction, and FIG. 6B is an explanatory diagram showing howthe light intensity distribution of the detection light beam in theZ-axis direction is adjusted so that the intensities of the detectionlight beams reflected by the target object Ob become equal to eachother.

In the optical position detection device 10 according to the presentembodiment, when the light emitting elements 12A, 12B are put onsimultaneously in the detection light beam detection period, thedistance detecting light intensity distribution L2Zab (the Z-coordinatedetecting light intensity distribution) in which the intensity decreasesmonotonically along the normal direction with respect to the firstsurface 41 is formed on the side (the detection area 10R) of the firstsurface 41 of the transmissive member 40 as shown in FIG. 6A. In thepresent embodiment, in the distance detecting light intensitydistribution L2Zab, the intensity decreases linearly as the distancefrom the first surface 41 of the transmissive member 40 increases, andin the X-axis direction, the intensity of the detection light beam L2 isconstant. Therefore, if the target object Ob is disposed in thedetection area 10R in the detection light beam detection period in thecondition of putting on the light emitting elements 12A, 12B whileputting off the light emitting element 12R for reference, the detectionlight beams L2 (the detection light beams L2 a, L2 b) are reflected bythe target object Ob, and some of the position detecting reflected lightbeam L3 is detected by the first light detector 30. Here, the lightreception intensity of the detection light beams L2 (the detection lightbeams L2 a, L2 b) in the first light detector 30 has a certainrelationship, for example, a proportional relationship, with theintensity corresponding to the position of the target object Ob in thedistance detecting light intensity distribution L2Zab.

In contrast thereto, when the light emitting element 12R for referenceis put on in the reference light detection period, the reference lightbeam L2 r emitted from the light emitting element 12R is partiallydetected by the first light detector 30. Here, since the reference lightbeam L2 r is never reflected by the target object Ob, the lightreception intensity Lr of the reference light beam L2 r in the firstlight detector 30 is constant irrespective of the position of the targetobject Ob as shown in FIG. 6A.

In the example shown in FIGS. 6A and 6B, the detection intensity of thereference light beam L2 r in the first light detector 30 is made equalto the intensity obtained when the first light detector 30 detects thedetection light beams L2 (the detection light beams L2 a, L2 b) when thetarget object Ob is located at a position immediately before havingcontact with the first surface 41.

By using such a distance detecting light intensity distribution L2Zaband the reference light beam L2 r, the distance LZ (the Z-coordinate)between the target object Ob and the transmissive member 40 can bedetected using the methods explained as follows.

For example, in a first method, a difference between the distancedetecting light intensity distribution L2Zab and the light receptionintensity Lr of the reference light beam L2 r in the first lightdetector 30 shown in FIG. 6A are used. More specifically, since thedistance detecting light intensity distribution L2Zab is previously setto a predetermined distribution, the difference between the distancedetecting light intensity distribution L2Zab and the intensity of thereference light beam L2 r in the first light detector 30 is previouslyset to a predetermined function. Therefore, the distance detectionsection 53 can detect the distance LZ (the Z-coordinate) between thetarget object Ob and the first surface 41 of the transmissive member 40by obtaining the difference between the detection value LZab in thefirst light detector when forming the distance detecting light intensitydistribution L2Zab in the detection light beam detection period and thedetection value Lr in the first light detector 30 when emitting thereference light beam L2 r in the reference light beam detection period.

According to such a method, even in the case in which the environmentlight Lc other than the detection light beams L2 such as the infraredcomponent included in the outside light enters the first light detector30, the intensity of the infrared component included in the environmentlight Lc is canceled out when obtaining the difference between thedetection values LZab, Lr, and therefore, the infrared componentincluded in the environment light Lc never exerts an influence on thedetection accuracy. Further, since the blank light beams L0 (the blanklight beams L0 a, L0 b, L0 r) are not included in the detection valuesLZab, LZr in the first light detector 30, the distance detection section53 can detect the distance (the Z-coordinate) of the target object Obbased on the detection result in the first light detector 30 withoutbeing affected by the blank light beams L0 (the blank light beams L0 a,L0 b, L0 r). It should be noted that it is also possible to detect theZ-coordinate of the target object Ob based on the ratio, the difference,or the ratio and the difference between the detection value obtainedwhen putting on the light emitting element 12A, the detection valueobtained when putting on the light emitting element 12B, and thedetection value Lr obtained when putting on the light emitting element12R.

Then as a second method there is adopted the method of detecting thedistance LZ (the Z-coordinate) between the target object Ob and thefirst surface 41 of the transmissive member 40 based on the adjustmentvalues when adjusting the control values (the drive current values) tothe light emitting elements 12A, 12B for position detection and thecontrol value (the drive current value) to the light emitting element12R for reference so that the detection value LZab in the first lightdetector 30 in the detection light beam detection period and thedetection value Lr in the first light detector 30 in the reference lightbeam detection period become equal to each other.

In such a method, firstly, as shown in FIG. 6A, in the detection lightbeam detection period, the light emitting elements 12A, 12B for positiondetection are put on while putting off the light emitting element 12Rfor reference to thereby obtain the detection value LZab in the firstlight detector 30 when forming the distance detecting light intensitydistribution L2Zab. Subsequently, in the reference light beam detectionperiod, the detection value Lr in the first light detector 30 when thelight emitting elements 12A, 12B for position detection are put offwhile putting on the light emitting element 12R for reference isobtained. On this occasion, if the detection value LZab in the firstlight detector 30 when forming the distance detecting light intensitydistribution L2Zab and the detection value Lr of the reference lightbeam L2 r in the first light detector 30 are equal to each other, it isunderstood that the target object Ob is located at the positionimmediately before having contact with the first surface 41.

In contrast thereto, if the detection value LZab in the first lightdetector 30 when forming the distance detecting light intensitydistribution L2Zab and the detection value Lr of the reference lightbeam L2 r in the first light detector 30 are different from each other,the control values (the drive current values) to the light emittingelements 12A, 12B for position detection and the control value (thedrive current value) to the light emitting element 12R for reference areadjusted so that the detection values LZab, Lr become equal to eachother. Then, as shown in FIG. 6B, the detection value LZab in the firstlight detector 30 when forming the distance detecting light intensitydistribution L2Zab is obtained again in the detection light beamdetection period, and the detection value Lr of the reference light beamL2 r in the first light detector 30 is obtained again in the referencelight beam detection period.

As a result, if the detection value LZab in the first light detector 30obtained when forming the distance detecting light intensitydistribution L2Zab and the detection value Lr of the reference lightbeam L2 r in the first light detector 30 become the value LZabr, namelyequal to each other, the distance detection section 53 can detect thedistance LZ (the Z-coordinate) between the target object Ob and thefirst surface 41 of the transmissive member 40 based on the ratio or thedifference between the adjustment value ΔL2Zab of the control values tothe light emitting elements 12A, 12B for position detection and theadjustment value ΔL2 r of the control value to the light emittingelement 12R for reference.

According to such a method, even in the case in which the environmentlight Lc other than the detection light beams L2 such as the infraredcomponent included in the outside light enters the first light detector30, the intensity of the infrared component included in the environmentlight Lc is canceled out when performing adjustment of the controlvalues to the light emitting elements 12A, 12B for position detectionand the light emitting element 12R for reference so that the detectionvalues LZab, Lr become equal to each other, and therefore, the infraredcomponent included in the environment light Lc never exerts an influenceon the detection accuracy. Further, since the blank light beams L0 (theblank light beams L0 a, L0 b, L0 r) are not included in the detectionvalues LZab, LZr in the first light detector 30, the distance detectionsection 53 can detect the distance (the Z-coordinate) of the targetobject Ob based on the detection result in the first light detector 30without being affected by the blank light beams L0 (the blank lightbeams L0 a, L0 b, L0 r).

It should be noted that although in the method described above thedistance LZ (the Z-coordinate) between the target object Ob and thetransmissive member 40 is detected based on the control values to thelight emitting elements 12A, 12B for position detection and the controlvalue to the light emitting element 12R for reference, it is alsopossible to detect the distance LZ (the Z-coordinate) between the targetobject Ob and the transmissive member 40 based on the light receptionresult in the second light detector 60 when controlling the lightemitting elements 12A, 12B, and 12R so that the detection values LZab,Lr become equal to each other.

It should be noted that although in the method described above both ofthe control values to the light emitting elements 12A, 12B for positiondetection, and the control value to the light emitting element 12R forreference are adjusted, it is also possible to adjust either one of thecontrol values.

When obtaining the position information of the target object Ob in theZ-axis direction based on the detection result in the first lightdetector 30 as described above, it is also possible to adopt aconfiguration of, for example, using a microprocessor unit (MPU) as theposition detection section 50, and thus executing predetermined software(an operation program) by the microprocessor unit, thereby performingthe process. Further, as explained with reference to FIGS. 5A and 5B, itis also possible to adopt a configuration of performing the process witha signal processing section using hardware such as a logic circuit.

Major Advantages of Present Embodiment

As explained hereinabove, in the optical position detection device 10according to the present embodiment, the light source section 11 emitsthe detection light beams L2 to form the light intensity distribution inthe detection area 10R. Further, the position detecting reflected lightbeams L3 reflected by the target object Ob are detected by the firstlight detector 30. Here, since the light intensity distribution has acertain relationship between the position in the detection area 10R andthe intensity, by previously figuring out the relationship between theposition and the intensity of the detection light beam, the positiondetection section 50 can detect the position of the target object basedon the light reception result of the first light detector 30.

Further, in the present embodiment, there is provided the second lightdetector 60 to which the position detecting reflected light beams L3reflected by the target object Ob in the detection area 10R out of thedetection light beams L2 emitted from the light source section 11 arenot input, and the blank light beams L0 not passing through thedetection area 10R enter the second light detector 60. Therefore, sincethe second light detector 60 can monitor the blank light beams L0irrespective of whether or not the target object Ob exists in thedetection area 10R, it is possible to set the emission intensities ofthe detection light beams L2 from the light source section 11 to optimumconditions based on the monitoring result. Therefore, since it is notrequired to monitor the blank light beams L0 by the first light detector30, it is possible to adopt the configuration in which the positiondetecting reflected light beams L3 enter the first light detector 30while the blank light beams L0 do not enter the first light detector 30.Therefore, since the influence of the blank light beams L0 is eliminatedfrom the light reception result in the first light detector 30, theposition detection section 50 can detect the position of the targetobject Ob without being unnecessarily affected by the blank light beamsL0.

Further, in the present embodiment, between the second light detector 60and the detection area 10R, there is disposed the light blocking member70 for preventing the position detecting reflected light beams L3reflected by the target object Ob from entering the second lightdetector 60. Therefore, the position detecting reflected light beams L3can be prevented from entering the second light detector 60 only byadding the configuration of providing the light blocking member 70.

Further, in the present embodiment, the transmissive member 40 isdisposed between the light source section 11 and the detection area 10R,and the blank light beams L0 are the light beams reflected by the secondsurface 42 of the transmissive member 40 out of the detection lightbeams L2 emitted from the light source section 11. Therefore, out of thedetection light beams L2 emitted from the light source section 11, theblank light beams L0 can be deflected toward the side on which thesecond light detector 60 is located.

Further, since the first light detector 30 has the light receivingsection 31 located close to the second surface 42 of the transmissivemember 40, the blank light beams L0 can be prevented from entering thefirst light detector 30 with a relatively simple configuration. Further,the second light detector 60 is disposed at a position overlapping thefirst light detector 30 in the normal direction with respect to thesecond surface 42 on the side opposite to the side on which thetransmissive member 40 is located with respect to the first lightdetector 30. Therefore, the position detecting reflected light beams L3can be prevented from entering the second light detector 60 with therelatively simple configuration of disposing the light blocking member70 between the first light detector 30 and the second light detector 60.

Further, in the optical position detection device 10 according to thepresent embodiment, since the light sources (the light emitting elements12) of the light source sections 11 are light emitting diodes, the lightsource section 11 can be configured to have a small size at a moderateprice. Further, since the first light detector 30 and the second lightdetector 60 are each composed of the light receiving elements such as aphotodiode or a phototransistor, the first light detector 30 and thesecond light detector 60 can be configured to have a small size at amoderate price.

Second Embodiment

As the first embodiment an example of detecting the distance LZ of thetarget object Ob from the transmissive member 40 and the X-coordinate ofthe target object Ob using the first light detector 30 is explained. Theexample of detecting the Y-coordinate of the target object Ob willfurther be explained with reference to FIGS. 7A, 7B, 8, 9A through 9D,and 10A through 10D.

Overall Configuration

FIGS. 7A and 7B are explanatory diagrams of a principal part of theoptical position detection device according to a second embodiment ofthe invention, wherein FIG. 7A is an explanatory diagram showing athree-dimensional arrangement of constituents of the optical positiondetection device, and FIG. 7B is an explanatory diagram showing atwo-dimensional arrangement of the constituents of the optical positiondetection device. FIG. 8 is an explanatory diagram showing an overallconfiguration of the optical position detection device according to thesecond embodiment of the invention. It should be noted that since thebasic configuration of the present embodiment is substantially the sameas in the first embodiment, common parts are denoted with the samereference symbols and the detailed explanation therefor will be omitted.

In FIGS. 7A, 7B, and 8, similarly to the case of the first embodiment,the optical position detection device 10 according to the presentembodiment is also an optical sensor device for detecting the positionof the target object Ob located on the side of a first surface 41 of thetransmissive member 40 having a sheet-like shape or a plate-like shape,and is used as a tactile sensor of a robot hand device described lateror a touch panel.

In order for performing such detection, the optical position detectiondevice 10 according to the present embodiment is provided with thetransmissive member 40 having a sheet-like shape or a plate-like shapeand having a first surface directed along the XY plane, a light sourcesection 11 for emitting detection light beams L2 from the side of thesecond surface opposite to the side of the first surface 41 in thetransmissive member 40, and the first light detector 30 for detectingposition detecting reflected light beams L3 reflected by the targetobject Ob and transmitted to the side of the second surface 42 of thetransmissive member 40.

In the present embodiment, the light source section 11 is provided withfour light emitting elements 12 (12A through 12D) for positiondetection, and the four light emitting elements 12A through 12D arelocated at respective positions distant from each other in both of theX-axis direction and the Y-axis direction, and have the respective lightemitting surfaces directed toward the transmissive member 40. The lightemitting elements 12A through 12D are each composed of a light emittingdiode (LED) or the like, and in the present embodiment, the lightemitting elements 12A through 12D respectively emit the detection lightbeams L2 a through L2 d, which are infrared light beams, as diverginglight beams.

The first light detector 30 is a photodiode having the light receivingsection 31 directed toward the transmissive member 40 and is disposed onthe side of the second surface 42 of the transmissive member 40, andbetween the positions at which the two light emitting elements 12A, 12Bare respectively disposed. The first light detector 30 is located on theside of the second surface 42 of the transmissive member 40 and has thelight receiving section 31 directed toward the second surface 42, andthe light receiving section 31 is disposed close to the second surface42.

Further, in the optical position detection device 10 according to thepresent embodiment, on the side of the second surface 42 of thetransmissive member 40 there is disposed a second light detector 60, andthe second light detector 60 also has a light receiving section 61directed toward the second surface 42 similarly to the first lightdetector 30. Similarly to the first light detector 30, the second lightdetector 60 is composed of a photodiode or a phototransistor, and in thepresent embodiment, a photodiode is used as the second light detector60.

Here, the second light detector 60 is disposed at a position overlappingthe first light detector 30 in the normal direction with respect to thesecond surface 42 on the side opposite to the side on which thetransmissive member 40 is located with respect to the first lightdetector 30. Further, in a space between the first light detector 30 andthe second light detector 60 included in a space between thetransmissive member 40 and the second light detector 60, there isdisposed a plate-like light blocking member 70, and therefore the lightblocking member 70 intervenes between the detection area 10R and thesecond light detector 60.

Similarly to the case of the first embodiment, also in the opticalposition detection device 10 thus configured, since the light receivingsection 31 of the first light detector 30 is opposed to the secondsurface 42, the position detecting reflected light beams L3 reflected bythe target object Ob in the detection area 10R enter the first lightdetector 30. It should be noted that since the light receiving section31 of the first light detector 30 is close to the second surface 42, theblank light beams L0 (the blank light beams L0 a, L0 b, L0 c, and L0 d),which are reflected by the second surface 42 of the transmissive member40 and fail to reach the detection area 10R, fail to enter the firstlight detector 30. In contrast thereto, since the first light detector30 and the light blocking member 70 intervene between the second lightdetector 60, and the transmissive member 40 and the detection area 10R,the position detecting reflected light beams L3 reflected by the targetobject Ob in the detection area 10R fail to enter the second lightdetector 60. It should be noted that since the light blocking member 70is fairly small in view of the size of the transmissive member 40 andthe distance between the light emitting elements 12, the blank lightbeams L0, which are reflected by the second surface 42 of thetransmissive member 40 and fail to reach the detection area 10R, enterthe second light detector 60.

It should be noted that in the present embodiment, environment light Lcsuch as outside light enters both of the first light detector 30 and thesecond light detector 60. Further, the reference light beam L2 r emittedfrom the light emitting element 12R for reference partially enters thefirst light detector 30, and partially enters the second light detector60 as the blank light beam L0 r.

In the present embodiment, the light source drive section 14 shown inFIG. 8 is provided with the light source drive circuit 140 for drivingthe light emitting elements 12, and the light source control section 145for controlling lighting pattern of each of the light emitting elements12 (the light emitting elements 12A through 12D) for position detectionand the light emitting element 12R for reference via the light sourcedrive circuit 140. The light source drive circuit 140 is composed oflight source drive circuits 140 a through 140 d, and 140 r forrespectively driving the five light emitting elements 12A through 12D,and 12R, and the light source control section 145 controls all of thelight source drive circuits 140 a through 140 d, and 140 r.

The position detection section 50 is electrically connected to the firstlight detector 30, and the detection result in the first light detector30 is output to the position detection section 50. In the presentembodiment, the position detection section 50 is provided with a signalprocessing section 55 provided with an amplifier and so on, anX-coordinate detection section 51, a Y-coordinate detection section 52,and a distance detection section 53 (a Z-coordinate detection section),and the light source drive section 14 and the position detection section50 operate in conjunction with each other to perform the positiondetection described later.

An emission intensity monitoring section 16 is electrically connected tothe second light detector 60, and the detection result in the secondlight detector 60 is output to the emission intensity monitoring section16. Such an emission intensity monitoring section 16 monitors theemission intensity of each of the light emitting elements 12 (the lightemitting elements 12A through 12D) for position detection and the lightemitting element 12R for reference based on the detection result of theblank light beams L0 by the second light detector 60, and the lightsource control section 145 sets an initial value of the emissionintensity of each of the light emitting elements 12 (the light emittingelements 12A through 12D) for position detection and the light emittingelement 12R for reference based on the monitoring result.

Position Detection Operation etc.

FIGS. 9A through 9D are explanatory diagrams of detection light beamsemitted from the respective light emitting elements 12 in the opticalposition detection device 10 according to the second embodiment of theinvention. FIGS. 10A through 10D are explanatory diagrams showing lightintensity distributions used for coordinate detection formed by thedetection light beams emitted from the light emitting elements 12 in theoptical position detection device 10 according to the second embodimentof the invention.

In the optical position detection device 10 according to the presentembodiment, the detection area 10R is set on the side of the firstsurface 41 of the transmissive member 40, and the light emittingelements 12A through 12D of the light source section 11 form the lightintensity distributions explained below.

Firstly, the detection area 10R has, for example, a rectangular shape,and the four light emitting elements 12A through 12D have respectivecentral optical axes directed toward the four corner portions 10Rathrough 10Rd of the detection area 10R. Therefore, when the lightemitting element 12A is put on, the light intensity distributioncentering on the corner portion 10Ra of the detection area 10R is formedas shown in FIG. 9A. Further, when the light emitting element 12B is puton, the light intensity distribution centering on the corner portion10Rb of the detection area 10R is formed as shown in FIG. 9B. When thelight emitting element 12C is put on, the light intensity distributioncentering on the corner portion 10Rc of the detection area 10R is formedas shown in FIG. 9C. Further, when the light emitting element 12D is puton, the light intensity distribution centering on the corner portion10Rd of the detection area 10R is formed as shown in FIG. 9D.

Therefore, if the light emitting elements 12A, 12D are in an on-stateand the other light emitting elements 12 are in an off-state, there isformed the X-coordinate detecting first light intensity distributionL2Xa (a first coordinate detecting light intensity distribution/a firstcoordinate detecting first light intensity distribution) in which theintensity of the detection light beam decreases monotonically in theX-axis direction from the one side X1 to the other side X2 as shown inFIG. 10A. In the present embodiment, in the X-coordinate detecting firstlight intensity distribution L2Xa, the intensity of the detection lightbeam L2 varies linearly in the X-axis direction from the one side X1toward the other side X2, and is constant in the Y-axis direction. Incontrast thereto, if the light emitting elements 12B, 12C are in anon-state and the other light emitting elements 12 are in an off-state,there is formed the X-coordinate detecting second light intensitydistribution L2Xb (a first coordinate detecting light intensitydistribution/a first coordinate detecting second light intensitydistribution) in which the intensity of the detection light beamdecreases monotonically in the X-axis direction from the other side X2to the one side X1 as shown in FIG. 10B. In the present embodiment, inthe X-coordinate detecting second light intensity distribution L2Xb, theintensity of the detection light beam L2 varies linearly in the X-axisdirection from the other side X2 toward the one side X1, and is constantin the Y-axis direction. Therefore, also in the optical positiondetection device 10 according to the present embodiment, theX-coordinate detection section 51 can detect the X-coordinate of thetarget object Ob similarly to the case of the first embodiment.

Further, if the light emitting elements 12A, 12B are in an on-state andthe other light emitting elements 12 are in an off-state, there isformed the Y-coordinate detecting first light intensity distributionL2Ya (a second coordinate detecting light intensity distribution/asecond coordinate detecting first light intensity distribution) in whichthe intensity of the detection light beam decreases monotonically in theY-axis direction from the one side Y1 to the other side Y2 as shown inFIG. 10C. In the present embodiment, in the Y-coordinate detecting firstlight intensity distribution L2Ya, the intensity of the detection lightbeam L2 varies linearly in the Y-axis direction from the one side Y1toward the other side Y2, and is constant in the X-axis direction. Incontrast thereto, if the light emitting elements 12C, 12D are in anon-state and the other light emitting elements 12 are in an off-state,there is formed the Y-coordinate detecting second light intensitydistribution L2Yb (a second coordinate detecting light intensitydistribution/a second coordinate detecting second light intensitydistribution) in which the intensity of the detection light beamdecreases monotonically in the Y-axis direction from the other side Y2to the one side Y1 as shown in FIG. 10D. In the present embodiment, inthe Y-coordinate detecting second light intensity distribution L2Yb, theintensity of the detection light beam L2 varies linearly in the Y-axisdirection from the other side Y2 toward the one side Y1, and is constantin the X-axis direction. Therefore, in the optical position detectiondevice 10 according to the present embodiment, the Y-coordinatedetection section 52 can detect the Y-coordinate of the target object Obusing a method substantially the same as the method of detecting theX-coordinate in the first embodiment.

Further, if all of the four light emitting elements 12 (the lightemitting element 12A, the light emitting element 12B, the light emittingelement 12C, and the light emitting element 12D) are put on, thedistance detecting light intensity distribution L2Zab explained in thefirst embodiment with reference to FIGS. 4A and 4B is formed. In such adistance detecting light intensity distribution L2Zab, the intensitydecreases monotonically along the direction of increasing the distancefrom the first surface 41 of the transmissive member 40, and such avariation can be made to be a linear variation by controlling the lightintensity distribution within the limited space of the detection area10R. Further, in the distance detecting light intensity distributionL2Zab, the intensity is constant along the X-axis direction and theY-axis direction. Therefore, also in the optical position detectiondevice 10 according to the present embodiment, similarly to the case ofthe first embodiment, the distance LZ (the Z-coordinate) between thetarget object Ob and the transmissive member 40 can be detected usingthe distance detecting light intensity distribution L2Zab and thedetection result in the first light detector 30. On this occasion, byusing the reference light beam L2 r, it is possible to cancel out theinfluence of the outside light and so on similarly to the case of thefirst embodiment.

Further, also in the present embodiment, similarly to the case of thefirst embodiment, there is provided the second light detector 60 towhich the position detecting reflected light beams L3 reflected by thetarget object Ob in the detection area 10R out of the detection lightbeams L2 emitted from the light source section 11 are not input, and theblank light beams L0 (the blank light beams L0 a, L0 b, L0 c, and L0 d)not passing through the detection area 10R enter the second lightdetector 60. Therefore, since the second light detector 60 can monitorthe blank light beams L0 irrespective of whether or not the targetobject Ob exists in the detection area 10R, it is possible to set theemission intensities of the detection light beams L2 from the lightsource section 11 to optimum conditions based on the monitoring result.Therefore, since it is not required to monitor the blank light beams L0by the first light detector 30, it is possible to adopt theconfiguration in which the position detecting reflected light beams L3enter the first light detector 30 while the blank light beams L0 do notenter the first light detector 30. Therefore, since the influence of theblank light beams L0 is eliminated from the light reception result inthe first light detector 30, there is exerted an advantage substantiallythe same as that of the first embodiment such that the positiondetection section 50 can detect the position of the target object Obwithout being unnecessarily affected by the blank light beams L0.

Third Embodiment

Although in the first and second embodiments described above the opticalposition detection device 10 is provided with the transmissive member40, it is also possible to apply the invention to the optical positiondetection device 10, which is not provided with the transmissive member40. In the case of such a configuration, for example, a deflectingmirror for reflecting some of the detection light beam L2, which isemitted from the light source section 11, toward the second lightdetector 60 is disposed between the light source section 11 and thedetection area 10R, and the detection light beam L2 reflected by thedeflecting mirror can be used as the blank light beams L0.

First Application Example of Optical Position Detection Device 10

A robot hand device using the optical position detection device 10, towhich the invention is applied, as a tactile sensor will be explainedwith reference to FIGS. 11A and 11B. FIGS. 11A and 11B are explanatorydiagrams of a robot arm having the optical position detection device 10to which the invention is applied provided to a hand device as a tactilesensor, wherein FIG. 11A is an explanatory diagram of the entire robotarm, and FIG. 11B is an explanatory diagram of the hand device.

The robot arm 200 shown in FIG. 11A is a device for performing, forexample, supply and takeoff of a work or a tool to and from anumerically controlled machine tool or the like, and is provided with acolumn 220 erecting from a base 290, and an arm 210. In the presentembodiment, the arm 210 is provided with a first arm section 230 linkedto the tip portion of the column 220 via a first joint 260, and a secondarm section 240 linked to the tip portion of the first arm section 230via a second joint 270. The column 220 is capable of rotating around ashaft line H1 perpendicular to the base 290, the first arm section 230is capable of rotating around a horizontal shaft line Hz at the tipportion of the column 220 due to the first joint 260, and the second armsection 240 is capable of rotating around a horizontal shaft line H3 atthe tip portion of the first arm section 230 due to the second joint270. At the tip portion of the second arm section 240, there is linked ahand 450 of the hand device 400, and the hand 450 is capable of rotatingaround a shaft line H4 of the second arm section 240.

As shown in FIG. 11B, the hand device 400 has the hand 450 provided witha plurality of gripping claws 410 (a gripping tool), and the hand 450 isalso provided with a disk-shaped gripping claw holding member 420 forholding the roots of the plurality of gripping claws 410. In the presentembodiment, the hand 450 is provided with a first gripping claw 410A anda second gripping claw 410B as the plurality of gripping claws 410. Asindicated by the arrow H5, both of the two gripping claws 410 arecapable of moving in a direction in which the gripping claws move awayfrom each other and a direction in which the gripping claws come closerto each other.

When gripping the target object Ob in the robot arm 200 configured asdescribed above, the column 220, the first arm section 230, and thesecond arm section 240 rotate in predetermined directions to therebymake the hand 450 come closer to the target object Ob (the work), andthen the two gripping claws 410 move in the direction in which the twogripping claws come closer to each other to thereby grip the targetobject Ob.

Here, the inside surfaces of the gripping claws 410 having contact withthe target object Ob when gripping the target object Ob (the work) areeach composed of the first surface 41 of the transmissive member 40 ofthe optical position detection device 10 explained in the first andsecond embodiments. Therefore, when the gripping claws 410 grip thetarget object Ob, the optical position detection device 10 detects therelative position between the target object Ob and the gripping claws410, and the position detection result is fed back to a drive controlsection of the gripping claws 410. Therefore, the gripping claws 410 canbe moved closer to the target object Ob at a high speed, and therefore,speeding-up of the gripping operation of the work can be achieved.Further, in the optical position detection device 10 according to thepresent embodiment, since the moment when the gripping claws 410 havecontact with the target object Ob can accurately be grasped, even afragile target object Ob or an extremely soft target object Ob can begripped without causing breakage of significant deformation to thetarget object Ob. In other words, when gripping the fragile targetobject Ob, the contact pressure of the gripping claw 410 can be setappropriately, and when gripping the soft target object Ob, a subductionamount of the gripping claws 410 to the target object Ob can be setappropriately.

Second Application Example of Optical Position Detection Device 10

A display device using the optical position detection device 10, towhich the invention is applied, as a touch panel will be explained withreference to FIGS. 12A and 12B. FIGS. 12A and 12B are explanatorydiagrams schematically showing a configuration of a display device witha position detection function provided with the optical positiondetection device 10 to which the invention is applied as a touch panel,wherein FIG. 12A is an explanatory diagram schematically showing anappearance of a principal part of the display device with a positiondetection function viewed from obliquely above, and FIG. 12B is anexplanatory diagram schematically showing an appearance thereof viewedfrom a lateral side.

The display device 100 with a position detection function shown in FIGS.12A and 12B is a projection display device and is provided with an imageprojection device 1200 called a liquid crystal projector or a digitalmicromirror device. Such an image projection device 1200 projects animage display light beam L1 in an enlarged manner from a projection lens1210 provided to a front face section 1201 of a housing 1250 toward thescreen member 1290.

The display device 100 with a position detection function according tothe present embodiment is provided with a function of opticallydetecting the position of the target object Ob in the detection area 10Rset in a front space (in front of the screen member 1290) from which theimage is projected, and displays the image in an area overlapping thedetection area 10R. The display device 100 with a position detectionfunction according to the present embodiment treats the XY-coordinate ofthe target object Ob as input information for designating, for example,a part of the image thus projected, and performs, for example, switchingof the image based on the input information.

With a view to realizing such a position detection function, in thedisplay device 100 with a position detection function according to thepresent embodiment, the optical position detection device 10 explainedin the first and second embodiments is used as a touch panel, and thescreen member 290 is composed of the transmissive member 40 of theoptical position detection device 10. Therefore, the screen surface onwhich the image is viewed in the screen member 290 is used as an inputsurface composed of the first surface 41 of the transmissive member 40,and on the side of the reverse side (the second surface 42 of thetransmissive member 40) of the screen member 290, there are disposed thelight source section 11 provided with the light emitting elements 12 forthe detection light beams, and the first light detector 30.

In the display device 100 with a position detection function thusconfigured, when indicating the image displayed on the screen member 290with the target object Ob such as a fingertip, the XY-coordinate and soon of the target object Ob are detected, and the position of the targetobject Ob can be treated as input information.

What is claimed is:
 1. A position detection device adapted to detect aposition of a target object, comprising: a light source section forminga light intensity distribution of a detection light beam; a first lightdetector receiving a reflected light beam of the detection light beamreflected by the target object; a transmissive member disposed between adetection area and the light source section, and between the detectionarea and the first light detector; a second light detector receiving alight beam reflected by the transmissive member out of the detectionlight beam emitted from the light source section; and a light blockingmember disposed between the second light detector and the transmissivemember, and adapted to block the reflected light beam.
 2. The positiondetection device according to claim 1, wherein the second light detectoris disposed at a position overlapping the first light detector in a planview with respect to a flat surface of the transmissive member.
 3. Theposition detection device according to claim 1, wherein the light sourcesection forms a first light intensity distribution in which theintensity varies in a direction from a first side toward a second sideopposite to the first side in the detection area, and a second lightintensity distribution having an intensity variation in a direction fromthe second side toward the first side that is different from the firstlight intensity distribution, and the position detection device detectsa position of the target object based on a comparison result between adetection result in the first light detector when forming the firstlight intensity distribution, and a detection result in the first lightdetector when forming the second light intensity distribution.
 4. Theposition detection device according to claim 1, wherein the light sourcesection forms a first light intensity distribution in which theintensity varies in a direction from a first side toward a second sideopposite to the first side in the detection area, and a second lightintensity distribution having an intensity variation in a direction fromthe second side toward the first side that is different from the firstlight intensity distribution, and varies an emission intensity of thedetection light beam so that the detection result in the first lightdetector when forming the first light intensity distribution and thedetection result in the first light detector when forming the secondlight intensity distribution become equal to each other, and theposition detection device detects a position of the target object basedon one of the emission intensity of the detection light beam aftervarying the emission intensity of the detection light beam and thedetection result in the second light detector.
 5. The position detectiondevice according to claim 3, wherein environment light enters the firstlight detector and the second light detector.
 6. A hand device providedwith a position detection device adapted to detect a position of atarget object, comprising: a light source section forming a lightintensity distribution of a detection light beam; a first light detectorreceiving a reflected light beam of the detection light beam reflectedby the target object; a transmissive member disposed between a detectionarea and the light source section, and between the detection area andthe first light detector; a second light detector receiving a light beamreflected by the transmissive member out of the detection light beamemitted from the light source section; a light blocking member disposedbetween the second light detector and the transmissive member, andadapted to block the reflected light beam; and a hand adapted to gripthe target object.
 7. A display device with a position detectionfunction adapted to detect a position of a target object, comprising: alight source section forming a light intensity distribution of adetection light beam; a first light detector receiving a reflected lightbeam of the detection light beam reflected by the target object; atransmissive member disposed between the detection area and the lightsource section, and between a detection area and the first lightdetector; a second light detector receiving a light beam reflected bythe transmissive member out of the detection light beam emitted from thelight source section; a light blocking member disposed between thesecond light detector and the transmissive member, and adapted to blockthe reflected light beam; and an image generation device adapted todisplay an image.